Islamabad, Oct 22 (IANS): The recent leak of heavy water at the Karachi Nuclear Power Plant (Kanupp) has environmentalists and civil society activists in Pakistan worried.

They are now raising questions over safety measures and operational protocols even as the government shut down the plant Thursday for an indefinite period, Dawn reported.

"The plant had already been closed on Oct 5 for three weeks for maintenance but after the leakage it will remain shut for an indefinite period," said Pakistan Atomic Energy Commission spokesman Ejaz Ahmed, adding that the leakage occurred during maintenance work Tuesday midnight.

Though unable to state the exact cause of leakage from a pipe, Ahmed said that it could only be ascertained after a proper inquiry. But he admitted no inquiry had yet been ordered.

The incident should be taken as a wake-up call; a thorough assessment of the plant should be made and old and obsolete components should be replaced, said a senior environmentalist who had worked with the IUCN - the World Conservation Union - and at various other international environment-related organisations, on condition of anonymity

According to the environmentalist, since the plant had outlived its designed life many years ago and was upgraded to expand its operations for a few more years, its boilers should be replaced and heat exchange system thoroughly examined and passed through a rigorous tolerance test.

Senior environmentalist F.H. Mughal, who maintained that after the incident, stricter vigil needed to be maintained because the plant was old, said the leakage from a pipe suggested that it was an old pipe and probably was not maintained properly.

He said strict safety measures should be taken because the plant was near Karachi.

Referring to the recent Fukushima nuclear disaster in Japan, Mughal said that even Britain had instituted a study to evaluate the effects on it of the Japanese accident, which was thousands of miles away.